Air core reactors are inductive devices used in high voltage power transmission, distribution and industrial applications. Configurations and designs include devices which have a number of applications, including filtering out harmonics, shunt devices which compensate for introduction of capacitive reactive power, and devices which limit short circuit currents. Air core reactors are formed with a series of concentrically positioned, spaced-apart winding layers, referred to as packages, in a cylindrical configuration. The winding layers are positioned between upper and lower current carrying members, sometimes referred to as spider units. The spider units comprise a series of arms radiating along a plane and away from a central position in a star configuration.
Among other functions, the spider units may serve as line terminals for connecting power lines and for connecting the winding layers in an electrically parallel configuration. The reactors are normally installed with the spider units in a horizontal orientation with respect to an underlying horizontal ground plane so that the major axis of the cylindrical configuration extends vertically upward from the ground plane. For a single reactor, or for the lower-most reactor in a stacked configuration of two or more reactors, the winding layers are supported above the ground by the lower spider unit and a series of insulators and structural leg members which extend from the lower spider unit to the ground.
The useful life of these reactors can be adversely affected by heat generated in and about the winding layers. With air core reactors typically placed in outdoor environments, conventional designs allow for some cooling by movement of air convection currents between the spaced-apart winding layers. These reactors have openings along the upper and lower spider units, allowing air currents to rise from the underlying ground plane, move along the direction of a central axis and pass above the upper spider unit.